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. A. HUNTER.

HOLDER-0N.

APPLICATION FILED MAY 6. I919.

Patented Nov. 25, 1919.

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Application filed May 6, 1919. Serial No. 295,228.

To all whom it may concern:

Be it known that I, ALBERT HUNTER, a citizen of the United States, residing at Portland, in the county of Multnomah and State of Oregon, have invented certain new and useful Improvements in Holders-On, of which the following is a specification.

The present invention relates to improvements in holders-on for pneumatic tools or riveting machines, designed for the purpose of backing up the rivets when driven by long stroke hammers of well known type, and the subject matter of the present invention, although not confined solely for the purpose, is specifically adaptable for use in ship construction when operating on the metal plates of the hull and other portions of the vessel.

The invention consists essentially in the novel combinations and arrangements with the riveting machine or pneumatic tool of the alined, extensible holder-on that is ad- -justable to suit the space between the part to be riveted and a fixed or stationary element against which the holder-on may be placed to back up the tool in its-movements.

In the accompanying drawings one complete example of the physical embodiment of the invention is illustrated the parts be ing constructed and combined according to the best mode so far devised for the practi cal application of the principles of the invention.

Figure 1 is a side view, in elevation, of a riveting machine or pneumatic tool equipped with the holder-on of the present invention.

Fig. 2 is an enlarged, detail view, partly broken away for convenience of illustration, of the invention as embodied in the device to be described.

In order to fully illustrate the invention I have depicted in the drawings a standard form of center piston type riveting machine or pneumatic holder-on 1 equipped with the usual air connection 2-, which includes the threaded tapered thimble 3 by means of which the holder-on is attached to the ma: chine.

The device of the invention includes a rack bar 4, of suitable dimensions and weight, that is screw threaded at one end to be entered and secured in the complementary thimble 3 of the riveting machine, and the device also includes the extension bar 5 that telescopes over the rackbar and is adjustable thereon longitudinally and guided and held against rotation thereon by means of the surface groove 6 in the rack bar and the screw or bolt 7 in the telescopic extension bar.

The extension bar is preferably a hollow or tubular member, as a metallic pipe and is slidable, within the limits of the groove 6, on the rack bar, and adjustable thereon through the instrumentality of the pivoted band 9 on the extension bar 5, and this pawl is normally held in engagement with the rack bar by the spring 10 between the handle 10 of the pawl and the extension bar 5. The extension bar is equipped with the usual tool point 11 held fixed by the set bolt 12.

In Fig. 1 the invention is illustrated in position for use on a ships bottom, the holder-011 being supported by the block 13, and the implement being arranged for use in vertical position so that the hammer 14 of the tool is alined with the extension device or holder-0n of the tool. here the necessity for using the tool in horizontal position arises, the tool is backed up against bracing or against the timbers of the shipway.

The extensible holder-on is adjusted approximately to the space to be occupied, and of course provision is made for the reciprocation of the riveting tool or head, and it will readily be apparent that the extension holder-on, when in proper position will perform the function of backing up the tool with efiiciency and satisfaction.

From the above description taken in connection with the drawings, it is evident that I have provided a device that fulfils the conditions of a comparatively perfect holderon for this purpose, as embodied in the following claims.

Having thus fully described my invenfrom what I claim as new and desire to secure bv Letters Patent is 1. The combination with the riveting tool and its alined rack bar, of a hollow extension bar on said rack bar, means for-preventing relative rotary movement of the bars, and a pivoted pawl on the extension bar engaging the rack bar for retaining the bars in adiusted position.

2. The combination with the riveting tool and its alined, longitudinally grooved, rack bar, of a telescoping bar having a screw extending in the groove and provided with a 65 pawl 8 movable in the ears 9 of the fixed pivoted pawl engaging the rack bar, as; deengaging the rack bar for retaining the bars scribed. V in adj ueted position, a tool point extending 3. The combination with the riveting tool from the extension bar, and means for ad- 10 and its alined rack bar, of a hollow GXtBIh j ustgibly supporting same therein.

sion bar on said rack bar, means for pre- In testimony whereofI aflix my signature. ventmg relative rotary movement of the bars, 2L pi oted pawl on the extension bar ALBERT HUNTER. 

